2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/129209Lectures on Siegel modular forms given in Nordfjordeid. Besides a survey on Siegel modular forms it presents the joint work with Carel Faber on vector-valued Siegel modular forms of genus 2 and it gives evidence for a conjecture of Harder on congruences between g=1 and g=2 forms.56 pages; minor revisionAlgebraic GeometryNumber Theory14K10text